The present invention relates to an improved engine fuel control systems, and more specifically to an engine fuel control system which compensates for changes in engine aspirated air due to changes in altitude, atmospheric temperature and/or barometric pressure as disclosed and claimed in our co-pending application Ser. No. 06/685,908 with the Title GAS-COUPLED TRANSDUCER DEVICE which is now abandoned; and as disclosed and claimed in our co-pending application Ser. NO. 06/788,634 with the title FUEL CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINES.
Several types of air flow rate sensing devices as part of engine fuel control systems are known to exist. One of which (a thermal flowmeter) is described in the U.S. Pat. No. 4,275,695. While being widely used, such thermal flowmeters are characterized by a multitude of shortcomings. Such as for instance, the pulsating, electric current flow within a heated wire located in the engine air induction tube, caused by pulsating heat exchange as a consequence of pulsating air flow in step with the opening and closing of the engine intake valves. Still other limitations may be found in the possible braking, and the formation of unwanted deposits on the heated wire. This, and other shortcomings may have adverse effects on the smooth operation of the engine fuel injection systems. To eliminate such shortcomings, requires extensive, and costly signal conditioning components. Other systems are described in the U.S. Pat. No. 4,311,042, and 4,457,167; whose principle of operation, except for the addition of electronic signal smoothing and linearizing components are basically as in the heretofore discussed system, and are therefore subject to basically the same limitations. While a still further U.S. patent with the U.S. Pat. No. 4,457,166 describes a device based on the subtraction of an appropriated number of Karman vortex pulses from a number of measured Karman vortex pulses.